Question

The element which has the least electron affinity is:

• A. Oxygen
• B. Lithium
• C. Carbon
• D. Fluorine

Answer 1

The correct option is A

Oxygen

The explanation for the correct option:

• Electron affinity is the amount of energy released when an electron is added to a neutral atom to form an anion.
• As we move from left to right in a period the electron affinity becomes more negative
• Oxygen is smaller in size hence electron density is more in Oxygen thus the inter-electronic repulsion is high.
• Therefore oxygen has the least electron affinity.

The explanation for wrong options:

Option B:

• As we move from left to right in a period electron affinity becomes more negative.
• Electron affinity of lithium is $59.6kJ/mol$.

Option C:

• Electron affinity decreases from left to right in a period.
• As carbon comes first while moving from left to right.
• Therefore electron affinity of carbon is greater than oxygen.

Option D:

• Fluorine has $7$ electrons and oxygen has $6$electrons in the valence shell.
• Hence the tendency of F to acquire additional electrons is higher compared to oxygen.
• Therefore fluorine has more electron affinity than oxygen.

Hence the correct option is Option A